Method and System for Time Based WLAN Scanning

ABSTRACT

Certain aspects of a method and system for time based wireless local area network (WLAN) scanning may include controlling scanning of a plurality of wireless access points in one or more WLANs by a WLAN station based on one or more factors comprising power consumed by the WLAN station based on the scanning, and/or a priority level of one or more media packets to be handled by the WLAN station. The information may be acquired for one or more of the plurality of wireless access points in one or more WLANs during the controlled scanning.

CROSS-REFERENCE TO RELATED APPLICATIONS/INCORPORATION BY REFERENCE

The present U.S. Utility Patent Application claims priority pursuant to35 U.S.C. §120, as a continuation, to the following U.S. Utility PatentApplication which is hereby incorporated herein by reference in itsentirety and made part of the present U.S. Utility Patent Applicationfor all purposes:

U.S. Utility application Ser. No. 12/355,015, entitled, “Method andSystem for Time Based WLAN Scanning”, filed Jan. 16, 2009, pending,which claims priority pursuant to 35 U.S.C. §119(e) to the followingU.S. Provisional Patent Application which is hereby incorporated hereinby reference in its entirety and made part of the present U.S. UtilityPatent Application for all purposes:

U.S. Provisional Application Ser. No. 61/122,123, entitled, “Method andSystem for Time Based WLAN Scanning”, filed Dec. 12, 2008.

The above stated applications are hereby incorporated by reference intheir entireties.

FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

MICROFICHE/COPYRIGHT REFERENCE

Not Applicable

FIELD OF THE INVENTION

Certain embodiments of the invention relate to wireless communication.More specifically, certain embodiments of the invention relate to amethod and system for time based wireless local area network (WLAN)scanning.

BACKGROUND OF THE INVENTION

Mobile communications have changed the way people communicate and mobilephones have been transformed from a luxury item to an essential part ofeveryday life. The use of mobile phones is today dictated by socialsituations, rather than hampered by location or technology. While voiceconnections fulfill the basic need to communicate, and mobile voiceconnections continue to filter even further into the fabric of every daylife, the mobile Internet is the next step in the mobile communicationrevolution. The mobile Internet is poised to become a common source ofevery day information, and easy, versatile mobile access to this datawill be taken for granted.

As the number of electronic devices enabled for wired and/or mobilecommunications continues to increase, significant efforts exist withregard to making such devices more power efficient. For example, a largepercentage of communications devices are mobile wireless devices andthus often operate on battery power. Additionally, transmit and/orreceive circuitry within such mobile wireless devices often account fora significant portion of the power consumed within these devices.Moreover, in some conventional communication systems, transmittersand/or receivers are often power inefficient in comparison to otherblocks of the portable communication devices. Accordingly, thesetransmitters and/or receivers have a significant impact on battery lifefor these mobile wireless devices.

Wireless local area network (WLAN) radio devices, such as those used in,for example, handheld wireless terminals, generally operate in the 2.4GHz (2.4000-2.4835 GHz) Industrial, Scientific, and Medical (ISM)unlicensed band. Other radio devices, such as those used in cordlessphones, may also operate in the ISM unlicensed band. While the ISM bandprovides a suitable low-cost solution for many of short-range wirelessapplications, it may also have some drawbacks when multiple usersoperate simultaneously. For example, because of the limited bandwidth,spectrum sharing may be necessary to accommodate multiple users.Multiple active users may also result in significant interferencebetween operating devices. Moreover, in some instances, microwave ovensmay also operate in this frequency spectrum and may produce significantinterference or blocking signals that may affect WLAN transmissions.

The devices using the IEEE 802.11 physical layer (PHY) and medium accesscontrol (MAC) layer may be referred to as stations or access points, forexample. The access points may enable distribution of data betweenendpoints. The MAC may also provide control frames for power managementand time synchronization, for example. The access points may provide atime synchronization beacon to associated stations in an infrastructurebasic service set (BSS). In an independent BSS, where stations areoperating as peers, an algorithm may be defined that may enable eachstation to reset its time when it receives a synchronization valuegreater than its current value. The stations entering a power-savingmode may inform a WLAN device through the frame control field of amessage, for example. The access point may then buffer transmissions tothe station. A station may wake up periodically to receive beacon framesand be informed that it has buffered transmissions waiting and thenrequest transmission. A station in active mode may be enabled to receiveframes at any time during a contention-free period. On the other hand, astation in a power-save mode may periodically enter the active mode toreceive beacons, broadcast, multicast, and buffered data frames.

Further limitations and disadvantages of conventional and traditionalapproaches will become apparent to one of skill in the art, throughcomparison of such systems with the present invention as set forth inthe remainder of the present application with reference to the drawings.

BRIEF SUMMARY OF THE INVENTION

A system and/or method for time based wireless local area network (WLAN)scanning, substantially as shown in and/or described in connection withat least one of the figures, as set forth more completely in the claims.

Various advantages, aspects and novel features of the present invention,as well as details of an illustrated embodiment thereof, will be morefully understood from the following description and drawings.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a block diagram of an exemplary WLAN infrastructure networkcomprising basic service sets (BSSs) integrated using a commondistribution system (DS), in accordance with an embodiment of theinvention.

FIG. 2 is a block diagram of an exemplary wireless network, inaccordance with an embodiment of the invention.

FIG. 3 is a diagram of an exemplary beacon frame format, in accordancewith an embodiment of the invention.

FIG. 4 is a diagram of an exemplary beacon frame body format, inaccordance with an embodiment of the invention.

FIG. 5 is a flow chart illustrating exemplary steps for time based WLANscanning, in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Certain aspects of a method and system for time based wireless localarea network (WLAN) scanning comprises controlling scanning of aplurality of wireless access points in one or more WLANs by a WLANstation based on one or more factors comprising power consumed by theWLAN station based on the scanning, and/or a priority level of one ormore media packets to be handled by the WLAN station. The informationmay be acquired for one or more of the plurality of wireless accesspoints in one or more WLANs during the controlled scanning.

FIG. 1 is a block diagram of an exemplary WLAN infrastructure networkcomprising basic service sets (BSSs) integrated using a commondistribution system (DS), in accordance with an embodiment of theinvention. Referring to FIG. 1, the exemplary WLAN infrastructurenetwork 100 shown may comprise a first BSS 102 a, a second BSS 102 b, aDS 104, a wired network 106, a portal 108, a first wireless access point(WAP) 112 a, a second WAP 112 b, and a plurality of WLAN stations(STAs). The BSSs 102 a and 102 b may represent a fundamental buildingblock of the IEEE 802.11 (WLAN) architecture and may be defined as agroup of stations (STAs) that are under the direct control of a singlecoordination function. The geographical area covered by a BSS is knownas the basic service area (BSA). The DS 104 may be utilized to integratethe BSSs 102 a and 102 b and may comprise suitable hardware, logic,circuitry, and/or code that may be enabled to operate as a backbonenetwork that is responsible for Medium Access Control (MAC) leveltransport in the WLAN infrastructure network 100. The DS 104, asspecified by the IEEE 802.11 standard, is implementation independent.For example, the DS 104 may be implemented utilizing IEEE 802.3 EthernetLocal Area Network (LAN), IEEE 802.4 token bus LAN, IEEE 802.5 tokenring LAN, Fiber Distributed Data Interface (FDDI) Metropolitan AreaNetwork (MAN), or another IEEE 802.11 wireless medium. The DS 104 may beimplemented utilizing the same physical medium as either the first BSS102 a or the second BSS 102 b. However, the DS 104 is logicallydifferent from the BSSs and may be utilized only to transfer packetsbetween the BSSs and/or to transfer packets between the BSSs and thewired network 106.

The wired network 106 may comprise suitable hardware, logic, circuitry,and/or code that may be enabled to provide wired networking operations.The wired network 106 may be accessed from the WLAN infrastructurenetwork 100 via the portal 108. The portal 108 may comprise suitablehardware, logic, circuitry, and/or code and may be enabled to integratethe WLAN infrastructure network 100 with non-IEEE 802.11 networks.Moreover, the portal 108 may also be enabled to perform the functionaloperations of a bridge, such as range extension and/or translationbetween different frame formats, in order to integrate the WLANinfrastructure network 100 with IEEE 802.11-based networks.

The WAPs 112 a and 112 b may comprise suitable hardware, logic,circuitry, and/or code that may be enabled to support range extension ofthe WLAN infrastructure network 100 by providing the integration pointsnecessary for network connectivity between the BSSs. The STA 110 a andthe STA 110 b correspond to WLAN-enabled terminals that comprisesuitable hardware, logic, circuitry, and/or code that may be enabled toprovide connectivity to the WLAN infrastructure network 100 via theWAPs. In an exemplary embodiment of the invention, the STA 110 a showncomprises a laptop computer and may correspond to a mobile station orterminal within the BSS and the STA 110 b shown is a desktop computerand may correspond to a fixed or stationary terminal within the BSS.Each BSS may comprise a plurality of mobile or fixed stations and maynot be limited to the exemplary implementation shown in FIG. 1.

In accordance with an embodiment of the invention, the WAP 112 a may beenabled to communicate information regarding neighbor candidate WAPs,for example, WAP 112 b to a STA, for example, the STA 110 a. The STA 110a may then utilize the information to schedule its tuning to a targetfrequency and execute identification and signal measurements for thetarget WAP in a minimum amount of time. The information may comprise,for example, beacon intervals or the periodicity of occurrence of beaconframes, a targeted beacon frame transmit time, or contention-free andcontention-based periods, for example. The information may becommunicated to the STA 110 a in an absolute time reference or arelative time difference to a known reference, for example. Theinformation for neighbor candidate WAPs, for example, the WAP 112 b maybe communicated to STAs, for example, STA 110 a using solicited and/orunsolicited broadcast/multicast-type frames, for example, included in abeacon frame, or solicited and/or unsolicited unicast-type MAC frames,for example, in association response frames, reassociation responseframes, or probe response frames. The information elements (IE)comprising information may be communicated in or as part of MACmanagement frames or may be piggybacked onto MAC control or data frames,for example. The information of neighbor candidate WAPs, for example,WAP 112 b may be generated in a particular WAP, for example, WAP 112 aby several methods. For example, the WAP 112 a may utilize network sidesignaling to retrieve information of neighboring WAPs, the WAP 112 a mayutilize its own measurements of neighbor WAPs, the WAP 112 a may utilizereports from STA measurements, or the WAP 112 a may utilize a generictiming device on the network.

In network side signaling, the WAPs 112 a and 112 b may exchangeinformation regarding the transmission time of their beacons through thedistribution system 104 connecting the WAPs 112 and 112 b together.There may be several possible implementations for network sidesignaling. For example, the WAP 112 a may broadcast informationregarding the timing of its beacon transmissions to all WAPs over thedistribution system 104, or the WAP 112 a may request beacon informationfrom another WAP, for example, WAP 112 b which may respond through thedistribution system 104. Alternatively, the WAP 112 a may be enabled toquery a network timing database, such as a central remote or localnetwork management entity to obtain current information about itsneighboring WAPs, for example, the WAP 112 b.

When the WAP 112 a uses its own measurements of neighbor WAPs, themeasuring WAP 112 a may listen to the beacons of other WAPs, forexample, WAP 112 b and measure the transmission time of the beacons.Based on the beacon transmission interval, the measuring WAP 112 a mayinfer approximate future transmission times, for example. In oneembodiment of the invention, the neighboring WAPs, for example, the WAP112 b may use the same frequency channel as the measuring WAP 112 a, forexample. In another embodiment of the invention, the measuring WAP 112 amay be enabled to tune to other frequency channels from time to time sothat the WAP 112 a may listen to the beacons.

In accordance with an embodiment of the invention, the STAs, forexample, STA 110 a may report to the coordinating WAP 112 a, the timesat which the STA 110 a receives a beacon frame from neighboring WAPsalong with beacon transmission intervals, the identity of theneighboring WAPs, for example, WAP 112 b and a timestamp of theneighboring WAP, for example, WAP 112 b. The coordinating WAP 112 a maybe enabled to utilize this combination of absolute and/or relative timereferences to derive the information. The coordinating WAP 112 a maystore this information in memory and infer approximate futuretransmission times of the beacon for these WAPs.

When a STA 110 a enters the BSS 102 a, the STA 110 a may be enabled toset a flag in the association request frame, in the reassociationrequest frame, or in the probe request frame. The flag may be utilizedto indicate that the STA 110 a wants to receive a neighbor WAP reportelement in the corresponding association response frame, reassociationresponse frame, or probe response frame, for example. The flag may beimplemented in various ways, for example, as a bit flag or as aninformation element comprising multiple values indicating the type ofinformation the STA 110 a desires to retrieve from the WAP 112 a. Theneighbor WAP report element may include a timing synchronizationfunction (TSF) information field, which may include a TSF offset valueand a beacon interval value for the neighbor WAP, for example, WAP 112b. The TSF offset value may be expressed in timing units (TUs), whichmay be, for example and without loss of generality one microsecond inlength, for example, and may be the timing offset between thecoordinating WAP 112 a and the neighbor WAP, for example, WAP 112 bexpressed in TUs relative to the coordinating WAP 112 a. The beaconinterval value may be expressed as a target beacon transmission time(TBTT), with a default value of 100 ms, for example. Notwithstanding,the invention may not be so limited and other suitable values may beutilized for the TBTT without limiting the scope of the invention.

The WLAN station, STA 110 a may be operable to scan a plurality ofaccess points, for example, 112 a and 112 b associated with the WLANstation, STA 110 a for a set time period to acquire information of theplurality of access points 112 a and 112 b. The WLAN station, STA 110 amay be operable to determine the power consumed by the WLAN station, STA110 a based on the scanning, and/or a priority level of one or moremedia packets to be transmitted by the WLAN station, STA 110 a. The WLANstation, STA 110 a may be operable to suspend the scanning of theplurality of access points, 112 a and 112 b based on the power consumedby the WLAN station, STA 110 a based on the scanning, and/or thepriority level of one or more media packets to be transmitted by theWLAN station, STA 110 a.

The acquired information may comprise a duration, a source address, adestination address, a basic service set ID (BSSID), a timestamp, abeacon interval, a service set ID (SSID), supported rates, frequencyhopping parameters, direct sequence spread spectrum parameters,contention free (CF) parameters, independent basic service set (IBSS)parameters, and/or setup configuration protocol (SP) information of abeacon frame received from the plurality of access points, 112 a and 112b.

FIG. 2 is a block diagram of an exemplary wireless network, inaccordance with an embodiment of the invention. Referring to FIG. 2,there is shown a plurality of wireless access points (WAPs) 202 and 230,a plurality of WLAN stations (STA), for example, STA 1 204, STA 2 206,STA 3 208, STA 4 210 and STA 5 212, a plurality of RF channels 214, 216,218, 220 and 222, and a network 210. Each of the plurality of WLAN STAs,STA 1 204, STA 2 206, STA 3 208, STA 4 210 and STA 5 212 may be awireless terminal such as a PC, a laptop, or a PDA with integrated orplug-in 801.11 capabilities. For example, the PC may utilize a wirelessNIC card and the laptop or PDA may comprise integrated 801.11capabilities. The network 210 may be a private or public network, forexample, a service provider or the Internet.

In operation, in instances where the WLAN STAs, STA 1 204, STA 2 206,STA 3 208, STA 4 210 and/or STA 5 212 are configured, they maycommunicate with the WAPs 202 and 204 via corresponding secure RFchannels 214, 216, 218, 220 and 222 respectively. The WAP 202 maycommunicate information received from configured WLAN STAs, STA 1 204,STA 2 206 and/or STA 3 208 via the network 210. The WAP 230 maycommunicate information received from configured WLAN STAs, STA 4 210and/or STA 5 212 via the network 210. In instances where the WLAN STAs,STA 1 204, STA 2 206, STA 3 208, STA 4 210 and/or STA 5 212 areunconfigured, they may communicate with the WAPs 202 and 230 functioningas configurators to request configuration information. The WAPs 202 and230 functioning as configurators may configure requesting WLAN STAs, STA1 204, STA 2 206, STA 3 208, STA 4 210 and STA 5 212 via a correspondingRF channel 214, 216, 218, 220 or 222 respectively.

In accordance with an embodiment of the invention, each of the WLANSTAs, for example, STA 1 204 may be operable to scan a plurality ofWAPs, for example, WAP 202 and WAP 230 for a set time period to acquireinformation of the plurality of WAPs 202 and 230. The acquiredinformation may be stored in the buffer 115.

FIG. 3 is a diagram of an exemplary beacon frame format, in accordancewith an embodiment of the invention. With reference to FIG. 3, there isshown a beacon frame format 302 with a time period, Tf equal to 10 ms,for example. The beacon frame 302 may comprise a frame control field304, a duration field 306, a destination address field 308, a sourceaddress field 310, a BSSID field 312, a sequence control field 314, abeacon frame body 316, and a frame check sequence (FCS) 318. The formatof the beacon frame may be based on specifications contained in IEEEstandard 802.11.

The frame control field 304 may comprise information that identifies theframe as being a beacon frame. The duration field 306 may compriseinformation indicating the amount of time that is to be allocated fortransmitting the beacon frame 302 and for receiving an acknowledgementof transmission. The destination address field 308 may compriseinformation identifying an address of one or more stations, such as, forexample, client station 254, that are intended to receive the beaconframe 302. The source address field 310 may comprise informationidentifying the address of the station that transmitted the beacon frame302. The BSSID field 312 may comprise information identifying theaddress of an WAP that is a current member of the basic service set(BSS), such as, for example BSS 202. The sequence control field 314 maybe utilized to identify a beacon frame that may be a segment within alarger protocol data unit (PDU). The beacon frame body 316 may compriseinformation that is specific to a beacon frame. The frame check sequence(FCS) field 318 may be utilized to detect errors in a received beaconframe 302.

In operation, the beacon frame 302 may be communicated by a WAP, suchas, for example, WAP 202, in a BSS, such as, for example, BSS 102 a. Thebeacon frame may enable stations within a BSS to locate a WAP within theESS. A station that is not a current member of the BSS may establish anassociation with the WAP based on the BSSID field.

In accordance with an embodiment of the invention, information may beacquired for one or more of the plurality of wireless access points inone or more WLANs during the controlled scanning The acquiredinformation may comprise a duration 306, a source address 310, adestination address 308, a basic service set ID (BSSID) 312, a framecontrol field 304, a sequence control field 314, and a frame check sum(FCS) 318 a.

FIG. 4 is a diagram of an exemplary beacon frame body format, inaccordance with an embodiment of the invention. With reference to FIG.4, there is shown a beacon frame body format 422. The beacon frame bodyformat 422 may comprise a timestamp field 424, a beacon interval field426, a capability information field 428, a SSID field 430, a supportedrates field 432, a frequency hopping (FH) parameter set field 434, adirect sequence spread spectrum parameter set field 436, a contentionfree (CF) parameter set field 438, an independent BSS (IBSS) parameterset field 440, a traffic information message field 442, and a setupconfiguration protocol (SP) information element (IE) field 444.

The timestamp field 424 may indicate a time at which the beacon framewas transmitted. The beacon interval field 426 may indicate the amountof time that may transpire between beacon frame transmissions. Thecapability information field 428 may be used to communicate capabilitiesrelated to a station, such as, for example, client station 204 thattransmits the beacon frame. The SSID field 430 may identify ESSmembership information of the station, such as, for example, clientstation 204, transmitting the beacon. The supported rates field 432 mayindicate data rates that may be supported by the station thattransmitted the beacon frame. The FH parameter set field 434 maycomprise information about stations that utilize frequency hopping. TheDH parameter set field 436 may comprise information about stations thatutilize direct sequence spread spectrum. The CF parameter set field 438may comprise information about WAPs, such as, for example, WAP 202 thatsupport contention free polling of stations in a BSS such as, forexample, BSS 102 a. The IBSS parameter set 440 may comprise informationabout stations that are members of an IBSS that do not comprise a WAPand do not access stations outside of the BSS via a DS such as, forexample, DS 210. The SP IE field 444 may comprise authorizationenablement information that is utilized by a configuration protocol.

In operation, a configurator, such as, for example, WAP 202 functioningas a configurator station 202 may transmit a beacon frame comprising theSP information element field 444. A station within a BSS may identify aconfigurator based on the source address field 310 of the beacon frame,and based upon the presence of a SP information element 444 in thebeacon frame body 316. The SP information element may compriseinformation that is not specified in IEEE standard 802.11. Ethernetframes that comprise the SP information element may be identified basedon the Ethertype field in the Ethernet frame header, where the Ethernetframe header may be as specified in IEEE 802.

In accordance with an embodiment of the invention, the acquiredinformation may comprise a timestamp 424, a beacon interval 426, aservice set ID (SSID) 430, capability information 428, supported rates432, frequency hopping parameters 434, direct sequence spread spectrumparameters 436, contention free (CF) parameters 438, independent basicservice set (IBSS) parameters 440, traffic information message 442and/or setup configuration protocol (SP) information 444 of a beaconframe 302 received from the plurality of WAPs 202 and 230.

FIG. 5 is a flow chart illustrating exemplary steps for time based WLANscanning, in accordance with an embodiment of the invention. Referringto FIG. 5, exemplary steps may begin at start step 502. In step 504, atime period for scanning of the plurality of access points and a waitperiod to allow media packets to be communicated may be set. In step506, a power threshold level of the WLAN station may be set. In step508, a priority level of WLAN signals to be transmitted by the WLANstation may be set. In step 510, scanning a plurality of access pointsassociated with the WLAN station may begin for the set time period toacquire information of the plurality of access points. The acquiredinformation may comprise a duration, a source address, a destinationaddress, a basic service set ID (BSSID), a timestamp, a beacon interval,a service set ID (SSID), supported rates, frequency hopping parameters,direct sequence spread spectrum parameters, contention free (CF)parameters, independent basic service set (IBSS) parameters, and/orsetup configuration protocol (SP) information of a beacon frame receivedfrom the plurality of access points. In step 512, the acquiredinformation based on the scanning may be stored in a buffer in the WLANstation. In step 514, the power consumed by the WLAN station based onthe scanning may be measured.

In step 516, it may be determined whether the power consumed by the WLANstation based on the scanning is lower than the set power thresholdlevel of the WLAN station. If the power consumed by the WLAN stationbased on the scanning is higher than the set power threshold level ofthe WLAN station, control passes to step 520. In step 520, the scanningmay be suspended for the duration of the set wait period. In step 522,one or more media packets may be transmitted and/or received for theduration of the wait period. Control then passes to step 524, where thescanning of the plurality of access points may be resumed. In instanceswhere the power consumed by the WLAN station based on the scanning islower than the set power threshold level of the WLAN station, controlpasses to step 518. In step 518, it may be determined whether thepriority level of one or more media packets to be transmitted and/orreceived by the WLAN station is lower than a priority of a WLAN signal.In instances where the priority level of one or more media packets to betransmitted and/or received by the WLAN station is higher than apriority of a WLAN signal, control passes to step 520, where thescanning may be suspended for the duration of the wait period. Ininstances where the priority level of one or more media packets to betransmitted and/or received by the WLAN station is lower than a priorityof a WLAN signal, control passes to step 519. In step 519, it may bedetermined whether the set wait period is equal to zero. If the waitperiod is not equal to zero, control passes to step 520. If the waitperiod is equal to zero, control passes to step 524. In step 524, thescanning of the plurality of access points may be resumed. Control thenreturns to step 510.

In accordance with an embodiment of the invention, a method and systemfor time based wireless local area network (WLAN) scanning may comprisea WLAN station, for example, STA 1 204 that is operable to controlscanning of a plurality of wireless access points, for example, WAPs 202and 230 in one or more wireless local area networks based on factorscomprising power consumed by the WLAN station STA 1 204, based on thescanning, and/or a priority level of one or more media packets to betransmitted and/or received by the WLAN station STA 1 204. Informationmay be acquired for one or more of the plurality of wireless accesspoints, for example, WAPs 202 and 230, in one or more wireless localarea networks based on the controlled scanning.

The acquired information comprises one or more of a duration, a sourceaddress, a destination address, a basic service set ID (BSSID), atimestamp, a beacon interval, a service set ID (SSID), supported rates,frequency hopping parameters, direct sequence spread spectrumparameters, contention free (CF) parameters, independent basic serviceset (IBSS) parameters, and/or setup configuration protocol (SP)information of a beacon frame received from the plurality of wirelessaccess points, for example, WAPs 202 and 230.

The WLAN station, STA 1 204 may be operable to suspend the scanning ofthe plurality of wireless access points, for example, WAPs 202 and 230,when the power consumed by the WLAN station, STA 1 204, based on thescanning is higher than a power threshold level of the WLAN station, STA1 204. For example, if the average power consumed by the WLAN station,STA 1 204 is around 1.5 Watts, the power threshold level of the WLANstation, STA 1 204, may be set to 1 Watt. In accordance with anembodiment of the invention, the power threshold level of the WLANstation, STA 1 204, may be user programmable. Notwithstanding, theinvention may not be so limited and other suitable power thresholdlevels may be utilized without limiting the scope of the invention. TheWLAN station, STA 1 204, may be operable to resume the suspendedscanning of the plurality of wireless access points, for example, WAPs202 and 230, when the power consumed by the WLAN station, STA 1 204,based on the scanning is lower than the power threshold level of theWLAN station, STA 1 204. The WLAN station, STA 1 204 may be operable tosuspend the scanning of the plurality of wireless access points, forexample, WAPs 202 and 230, when the priority level of the media packetsis higher than a priority level of a WLAN signal. For example, one ormore audio and/or video packets to be transmitted and/or received by theWLAN station, STA 1 204, may have a higher priority level than thepriority level of a WLAN signal to be transmitted and/or received by theWLAN station, STA 1 204. The WLAN station, STA 1 204 may be operable toresume the suspended scanning of the plurality of wireless accesspoints, for example, WAPs 202 and 230, when the priority level of theone or more media packets is lower than the priority level of the WLANsignal.

Another embodiment of the invention may provide a machine and/orcomputer readable storage and/or medium, having stored thereon, amachine code and/or a computer program having at least one code sectionexecutable by a machine and/or a computer, thereby causing the machineand/or computer to perform the steps as described herein for time basedwireless local area network (WLAN) scanning.

Accordingly, aspects of the invention may be realized in hardware,software, firmware or a combination thereof. The invention may berealized in a centralized fashion in at least one computer system or ina distributed fashion where different elements are spread across severalinterconnected computer systems. Any kind of computer system or otherapparatus enabled for carrying out the methods described herein issuited. A typical combination of hardware, software and firmware may bea general-purpose computer system with a computer program that, whenbeing loaded and executed, controls the computer system such that itcarries out the methods described herein.

One embodiment of the present invention may be implemented as a boardlevel product, as a single chip, application specific integrated circuit(ASIC), or with varying levels integrated on a single chip with otherportions of the system as separate components. The degree of integrationof the system will primarily be determined by speed and costconsiderations. Because of the sophisticated nature of modernprocessors, it is possible to utilize a commercially availableprocessor, which may be implemented external to an ASIC implementationof the present system. Alternatively, if the processor is available asan ASIC core or logic block, then the commercially available processormay be implemented as part of an ASIC device with various functionsimplemented as firmware.

The present invention may also be embedded in a computer programproduct, which comprises all the features enabling the implementation ofthe methods described herein, and which when loaded in a computer systemis able to carry out these methods. Computer program in the presentcontext may mean, for example, any expression, in any language, code ornotation, of a set of instructions intended to cause a system having aninformation processing capability to perform a particular functioneither directly or after either or both of the following: a) conversionto another language, code or notation; b) reproduction in a differentmaterial form. However, other meanings of computer program within theunderstanding of those skilled in the art are also contemplated by thepresent invention.

While the invention has been described with reference to certainembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted withoutdeparting from the scope of the present invention. In addition, manymodifications may be made to adapt a particular situation or material tothe teachings of the present invention without departing from its scope.Therefore, it is intended that the present invention not be limited tothe particular embodiments disclosed, but that the present inventionwill include all embodiments falling within the scope of the appendedclaims.

What is claimed is:
 1. A method for wireless communication, the methodcomprising: obtaining, at a wireless station, information about acandidate wireless access point (WAP) from a current WAP, wherein theinformation is related to communication with the candidate WAP;processing the information about the candidate WAP, using processingcircuitry of the wireless device, to determine a time to tune thewireless device to a target frequency used by the candidate WAP forwireless communication; and tuning to the target frequency at the timedetermined.
 2. The method according to claim 1, wherein the informationabout the candidate WAP comprises: information indicating a beaconinterval associated with the target WAP.
 3. The method according toclaim 1, wherein the information about the candidate WAP comprises:timing information provided in an absolute time reference.
 4. The methodaccording to claim 1, wherein the information about the candidate WAPcomprises: timing information provided in a relative time referenceindicating a timing difference relative to a known timing reference. 5.The method according to claim 1, wherein the obtaining comprises:receiving the information about the candidate WAP in a beacon framegenerated by the current WAP.
 6. The method according to claim 1,wherein the obtaining comprise: receiving the information about thecandidate WAP in a response frame generated by the current WAP.
 7. Themethod according to claim 1, wherein the obtaining comprises: receivingthe information about the candidate WAP as part of a media accesscontrol (MAC) layer frame.
 8. A wireless local area network (WLAN)station comprising: wireless circuitry configured to receive, via aWLAN, information about a candidate wireless access point (WAP) from acurrent WAP, wherein the information is related to communication withthe candidate WAP; a processor configured to process the informationabout the candidate WAP to determine a time to tune the wirelesscircuitry to a target frequency used by the candidate WAP for wirelesscommunication; and the processor further configured to tune the wirelesscircuitry to the target frequency at the time determined.
 9. The WLANstation according to claim 8, wherein the information about thecandidate WAP comprises: information indicating a beacon intervalassociated with the target WAP.
 10. The WLAN station according to claim8, wherein the information about the candidate WAP comprises:information obtained by the current WAP from the candidate WAP
 11. TheWLAN station according to claim 10, wherein the information about thecandidate WAP comprises: information obtained via side signaling. 12.The WLAN station according to claim 8, wherein the processor is furtherconfigured to: process a beacon frame generated by the current WAP toobtain the information about the candidate WAP.
 13. The WLAN stationaccording to claim 8, wherein the processor is further configured to:obtain the information about the candidate WAP from a reassociationresponse frame.
 14. The WLAN station according to claim 8, wherein: theinformation about the candidate WAP is obtained by measurements made bythe current WAP.
 15. A system for wireless communication, the systemcomprising: a wireless local area network (WLAN) station configured tobe wirelessly coupled to a wireless access point (WAP); the WLAN stationincluding: circuitry configured to receive, from the WAP, informationabout a candidate wireless access point (WAP); a processor configured toprocess the information about the candidate WAP schedule tuning to atarget frequency used by the candidate WAP for wireless communication;and the processor further configured to tune the wireless circuitry tothe target frequency according to the schedule.
 16. The system accordingto claim 15, wherein the information about the candidate WAP comprises:information indicating a beacon interval broadcast by the target WAP.17. The system according to claim 15, wherein the information about thecandidate WAP comprises: information obtained by measuring communicationcharacteristics of the candidate WAP.
 18. The system according to claim15, wherein the information about the candidate WAP comprises:information obtained via side signaling.
 19. The system according toclaim 15, wherein the processor is further configured to: process abeacon frame generated by the WAP to obtain the information about thecandidate WAP.
 20. The system according to claim 15, wherein theprocessor is further configured to: obtain the information about thecandidate WAP from a response frame.